Manhole skirt assembly and kit

ABSTRACT

A manhole assembly is usable in combination with an underground tank assembly, and essentially comprises a double-walled, lid-supporting skirt assembly. The skirt assembly comprises inner and outer isolation walls. The inner isolation wall defines an inner manhole cavity and a moisture-directing, outer manhole channel. The outer manhole channel extends intermediate the inner isolation wall and the outer isolation wall. The outer manhole channel directs moisture from the superior skirt end adjacent a manhole lid supported by skirt assembly to the inferior skirt end thus isolating the inner manhole cavity from channel-directed moisture. The manhole assembly may further comprise a spring-actuable, lid-compressible collar assembly. It is contemplated that the collar assembly may be cooperable with the lid for selectively allowing matter to pass through the outer manhole channel depending on whether the lid is seated upon the collar assembly or removed therefrom.

PRIOR HISTORY

This application is a continuation-in-part patent application claiming the benefit of pending U.S. patent application Ser. No. 11/237,290, filed in the United States Patent and Trademark Office on Sep. 28, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a manhole skirt assembly for use in combination with an underground storage tank. More particularly, the present invention relates to a moisture-diverting manhole skirt assembly or kit for outfitting underground storage tank assemblies and the like.

2. Description of the Prior Art

Those experienced with underground storage tanks and the maintenance thereof must often address the fact that many of the underground storage tanks suffer from aged, deteriorated, and contaminated fill locations. In this regard, it is noted that manhole type entranceways to underground storage tanks all suffer from moisture infiltration that occurs when moisture from rain, snow, and the like accumulates. The moisture generally permeates into the manhole type entranceway at the lid/lid rest junction. Countless attempts have been made to make a waterproof manhole assembly, all of which exhibit a poor end result, namely, a water-permeable manhole assembly.

When moisture enters a manhole assembly in superior adjacency to an underground storage tank, the moisture tends to pool upon underground storage tank components, thereby infiltrating and often damaging said components. By providing a moisture-redirecting structure or chamber with a larger drainage area, the moisture that inevitably enters a manhole assembly may be redirected away from inner chamber or moisture-sensitive components. A structural feature of this type then allows internal components to be isolated from damaging moisture and further allows visual inspection and moisture-free access to internal components.

It is further noted that the effects of petroleum products entering, and contaminating ground water from spills, and leaks are well documented, there being a great deal of documentation detailing the negative effects of contaminated ground water. Obviously, if a leak or spill can be prevented the environment will benefit. In an effort to protect the environment from leaks and spills of the type here noted the United States Congress enacted the Underground Storage Compliance At of 2003. The Act attempts to regulate the use of underground storage tanks and thus attempts to foster improvements to underground storage tank systems to minimize spillage and soil contamination.

In addition to federal law(s), many local and state laws have also been written to regulate the use of underground storage tank systems. Often, however, the conditions surrounding the underground storage tanks are in violation of any number of local, state, and/or federal laws. In this regard, it is noted that all current fill locations at underground storage tanks must have an overspill (OS) device capable of holding at least 5 gallons of liquid. This device is practical and is used for a collection vessel upon the draining hoses after a fill delivery is made. The OS device has a small opening at the top of the device approximately 9 to 10 inches in diameter, which opening allows access to the fill riser pipe that is connected to the tank top and is used as the port for liquid delivery. The existing overspill or OS devices are designed to be water tight at installation and most contain a drain port allowing drainage of the device through said port to the fill riser pipe. The overspill device is typically accessible by opening a manhole lid at the grade of the concrete drive and is designed to act as a spill catch for fuel delivery drivers draining the delivery hose from the delivery truck after dropping/delivering a load of product. This mandatory OS device has proven effective and has contained a great deal of spillage, there being on the order of 700,000 active underground storage tanks in the United States.

As time has gone by many of the OS devices have started to show wear and attendant contamination. Indeed, it is rare to find a fill location that has no contamination present. Existing OS devices thus, do not come close to offering a complete solution to the spillage, leakage, and contamination problems that still exist at underground storage tanks. A number of means for secondarily containing spillage adjacent underground storage tanks has arisen. Indeed, all underground storage tank components (including tanks, product piping, dispensers, and pumps) of the underground tank system that hold, or transfer liquids must also be secondarily contained (except for the most spill prone, used, overlooked, component the OS location, namely, the fill port).

The underground storage tank assembly typically has an outer containment tank with monitoring capability as achieved by a sensor installed at the interstitial space between the walls of said tank. The pumping devices are located on the top of the underground storage tank and have a secondary containment sump that acts as a collection device for liquids in case of a leak. The sump is also usually monitored by a sensor. The piping from the pump/suction device at the tank top sump is secondarily contained by the primary piping being surrounded by a larger diameter pipe from the tank top sump to the dispensing location. The dispensing location (pump or dispenser) also typically has a sump located beneath the dispensing device. The dispenser/pump sump is monitored via a sensor. All of the major components that contain and hold fuel at an underground storage tank system are thus secondarily contained and have the capability of being monitored at the tank monitoring systems. Almost all underground storage tank systems have a tank monitoring system that, when in alarm status, will give an audible warning and a print out of the alarm condition.

Perhaps the most used, spill prone, and volatile point of an underground storage tank is the fill port. It then follows that the most used, spill prone, and volatile port of the underground storage tank system should be secondarily contained. As earlier noted, there are approximately 700,000 active underground storage tanks in the United States, and the amount of spillage at and around the existing OS locations of these 700,000 underground storage tanks on a daily basis is often not reported and/or cleaned. It then follows that a great deal of petroleum product enters and contaminates groundwater supplies. Clearly secondary containment of the fill port location of underground storage tanks is useful, if not essential.

Current methods of containing spillage at the fill location of underground storage tanks by an overspill device are lacking in certain respects. The most notable problems may be listed, as follows: 1) a relatively small 9-10 inch opening at the top of the OS device (the small opening does not allow much room for delivery error or missed spillage. 2) Upon completion of installation of an OS device, and after a period of time, a build up of debris/silt forms a dam between the skirt material of the manhole and the OS device allowing water infiltration and build up of debris/silt surrounding the OS device. 3) The water/silt build up also damages the lid assembly and components of the OS device (making the initial water tight capability obsolete, and thus allowing debris, silt, or water to infiltrate the OS device, thus damaging the drain device of the OS device, and thus the probability of the water, silt, and debris infiltrating the UG storage tank. 4) The area outside of the OS device is a release point to the environment (soil, groundwater). When a spill occurs outside of the small opening at the OS device the spill is a release into the environment. Spillage of even the smallest amounts will build up over the lifetime of the underground storage tank system and will create certain far-reaching environmental problems. 5) Most currently used OS devices do not have means for containing, monitoring, or receiving notification of spillage or water infiltration with the use of the OS device. 6) When liquid spillage occurs outside of the OS device, the tank owner is held liable, and in most cases will not otherwise be advised of the spillage.

It is noted that while the prior art attempting to address secondary containment of underground fill/overfill area with particular attention being given to moisture-redirective manhole assemblies for use in combination with underground storage tanks is rather poorly developed. A brief listing of certain relatively ineffective prior art specifically relating to secondary spillage containment systems and the like, is briefly described, hereinafter.

U.S. Pat. No. 4,655,361 ('361 Patent), which issued to Clover et al., discloses a Containment Tank. The '361 Patent teaches a secondary containment tank and manhole cover assembly. The assembly provides access to a fill pipe for a main underground storage tank and prevent overflow of excess volatile liquid such as gasoline into the ground. The containment tank includes an upper ring or rim secured on an in-ground vertical skirt supported in a concrete base. An inner container is secured to the vertical skirt and has an open end adjacent to the upper ring. The cover fits into and is supported on a horizontal flange or step of the upper ring over the opening of the inner container and includes a vertical ring extending downwardly from the underside of the cover into a space between the inner container and vertical skirt. The vertical ring on the cover extends below the level of the container opening and thus bypasses any surface water leakage through the upper ring around the cover into the space adjacent to the container and into the ground below. The upper containment tank also includes means such as a manually operable sump pump or drain valve to empty excess liquid into the fill pipe of the main storage tank.

U.S. Pat. No. 4,706,718 ('718 Patent), which issued to Milo, discloses a Containment Manhole having Spillage Sealing Means. The '718 Patent teaches a containment manhole comprising a hollow body having a closed bottom and an open top. A concentric opening is provided in the bottom to receive an underground tank fill therethrough and a circular, resilient seal is provided to seal the junction between the tank fill and the manhole bottom. Optionally, a drain valve may be provided in the manhole bottom to lead any spillage directly back to the tank fill. The manhole terminates upwardly in the machined ring and includes a gasketed junction with the ring. The ring includes an upper shoulder upon which the cover peripheral lip can rest and a lower shoulder of size to enable the cover peripheral edges to rest. An O-ring seal is provided intermediate the cover and the top ring to provide a first sealed junction and a circular gasket is affixed on the lower ring edge to provide a second seal when the cover is in position.

U.S. Pat. No. 4,717,036 ('036 Patent), which issued to Dundas et al., discloses a Liquid Tank Spillage Control System. The '036 Patent teaches a spill control device for underground liquid storage tanks having an upwardly extending fill pipe. The control device comprises a steel, epoxy coated, and liquid collecting spill tank having a riser tube that extends upward through the tank bottom. A circular seal ring fits about the upper end of the riser tube and about the outer wall of a fill pipe received through the riser tube. A clamp compresses the seal about both the riser tube and fill pipe. A liquid impermeable cover is provided which covers the access opening in the top of the spill tank. A first basin surrounds the cover for channeling precipitation, and other liquids impinging the cover, away from the spill tank. A valve is disposed on the fill pipe for selectively directing liquids discharged into the spill tank into the storage tank. A second basin surrounds the spill tank for recovering liquids discharged from the spill tank during a filling operation.

U.S. Pat. No. 4,762,440 ('440 Patent) and U.S. Pat. No. 4,842,443 ('443 Patent), both of which issued to Argandona, disclose certain Spill Containment Device(s). The '440 and '443 Patents teach spill containment devices for the fill tube of a liquid storage tank, particularly an underground, liquid storage tank. The containment devices each have a spill container with a bottom opening for receiving the tank fill tube in liquid sealing relation to the container wall and a top opening through which the fill tube is accessible for filling the tank, whereby the container contains any liquid spill during filling of the tank. The container top openings are closed by removable covers which cooperate with a water drain arrangement to vent liquid vapor from the containers while preventing rain and other ground surface water from entering the containers. A drain valve operable from a position adjacent each container top opening is provided for draining liquid spill from the respective container to the tank. One embodiment is designed to receive multiple tank fill tubes and has a surrounding casing with a relatively massive top end closure having openings closed by separate relatively small covers which are individually removable to access the different tank fill tubes.

U.S. Pat. No. 5,058,633 ('633 Patent), which issued to Sharp, discloses a Containment Assembly for Fill Pipe of Underground Storage Tanks. The '633 Patent teaches an assembly intended for use on underground storage tanks. The assembly provides ready access to a fill pipe from ground level. At the same time the assembly serves as a spill containment means for accidental spillage and a secondary containment means for the fill pipe. The assembly of the invention comprises a secondary containment chamber having a sidewall with means for attaching to the storage tank. An anchor ring which is attached to an upper open end of the containment chamber acts as a permanent ground base for the assembly. A bridging surface cover within the anchor ring has a removable lid positioned in its interior portion to gain access to the chamber's interior for a filling operation. The assembly also comprises a fill pipe for delivering liquid to the storage tank. The fill pipe is positioned within the secondary containment chamber with a discharging end extending through the chamber's bottom and a receiving end terminating within the chamber but near the bridging surface cover. An open top spill compartment is positioned within the secondary containment chamber and at the receiving end of the fill pipe so as to encompass the fill pipe's receiving end for the purpose of catching any spilled liquid from the filling operation. The spill compartment also prevents any of the spilled liquid and vapors from entering the secondary containment chamber.

U.S. Pat. No. 5,222,832 ('832 Patent), which issued to Sunderhaus et al., discloses Spill Containment Devices and Their Installation. The '832 Patent teaches a below grade, spill containment device for connection with the riser pipe of an underground fuel storage tank. The containment device is disposed within and isolated from a manhole, which is mounted in a concrete apron. The containment device comprises a compositely formed container, rigidly mounted on the riser pipe. The container formed of structural synthetic resin material elements held in assembled relation by snap fitted lugs and notches. A lid, for closing the upper, access opening, is mounted on a pivotable arm. A lever pivoted on the arm selectively engages latch means to lock the lid in a closed position. A projection on the lever prevents the manhole cover from seating if the lever is not in its lock position. A valve for draining fuel from the container to the riser pipe is closed when the lid is open and opened when the lid is closed. The manhole and the containment device are packaged in a shipping carton in spaced relation be corrugated paper sheets. These sheets are employed in obtaining a desired relation between the containment device and manhole in the installation of these components, which involve pouring a concrete apron around the upper end of the manhole. An alternative system employs adjusting nuts to obtain this relationship between the manhole and containment device. In one embodiment the manhole is compositely formed to permit relative movement between its upper and lower portions, after installation.

U.S. Pat. No. 6,655,418 ('418 Patent), which issued to McGill et al., discloses a Drop Tube Seal for Petroleum Underground Storage Tanks. The '418 Patent teaches a drop tube sealing assembly. The assembly may contain a riser pipe having a proximal end with internal threads and an underground storage tank spaced apart from the proximate end of the riser pipe. The storage tank may contain a threaded inlet which is positioned atop the tank. A pipe nipple may include a first end in cooperation with the proximal end, an opposite end in cooperation with the threaded inlet, and an annular inner surface that forms a conduit. The inner surface may comprise a female thread section. A drop tube adapter fitting may be concentrically disposed within the pipe nipple. The adapter fitting may contain an outer surface containing external threads in cooperation with the female thread section. A seal in the form of an O-ring may be disposed between the adapter fitting and the pipe nipple. A drop tube having an open end may be coupled to the adapter fitting.

It will be seen from a further review of the above-referenced patents and other prior art generally known to exist relating to underground storage tank spillage containment systems, that the prior art does not teach a double-walled manhole skirt assembly in combination with primary or secondary spillage containment assemblies as situated in superior adjacency to underground storage tank assemblies. Further, the prior art does not teach a matter isolation kit installable upon an underground storage tank assembly comprising for directing moisture away from moisture-sensitive underground storage tank assembly components. The prior art thus perceives a need for a matter isolation system and kit comprising a double-walled manhole skirt assembly optionally usable in combination with underground storage tank assemblies and/or primary and secondary spillage containment assemblies associated therewith.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a double-walled manhole skirt assembly and/ or kit, which when outfitted upon an underground storage tank assembly functions to direct moisture away from the inner manhole cavity and structure commonly found therein. The present invention thus teaches a manhole assembly designed most specifically for use in combination with an underground tank assembly and comprises a manhole lid and a skirt assembly. The lid comprises a superior lid surface and an inferior lid surface. The skirt assembly comprises a double-walled, lid-supporting skirt having an inner isolation wall, an outer isolation wall, a superior skirt end, and an inferior skirt end. The inner isolation wall defines an inner manhole cavity and a moisture-directing, outer manhole channel. The outer manhole channel extends intermediate the inner isolation wall and the outer isolation wall, the inner isolation wall aids in the support of the manhole lid at the inferior lid surface. The outer manhole channel directs moisture from the superior lid surface to the inferior skirt end thus isolating the inner manhole cavity from channel-directed moisture.

The outer isolation wall may be bell-shaped for maximizing the radial distance intermediate the inner and outer isolation walls at the inferior skirt end. It is contemplated that the maximized radial distance intermediate the inner and outer isolation walls at the inferior skirt end may well enhance moisture redirection away from the inner manhole cavity. The inner and outer isolation walls may be provided in sections. Thus, the inner and outer isolation walls may comprise transversely sectioned upper and lower annular portion(s) or a plurality of longitudinally sectioned arc length portions. It is contemplated that providing the sections may well ease stowage space, for example, when in the knock-down state.

The manhole assembly may further comprise a spring-actuable, lid-compressible collar assembly. It is contemplated that the collar assembly may interface intermediate the lid and the inner isolation wall, and comprise a collar member and certain spring-actuating means. The collar member may further comprise certain channel-gating structure. The spring-actuating means, when compressed by the lid as seated upon the collar member, function to open the outer manhole channel via the channel-gating structure for allowing matter to pass through the outer manhole channel. When the lid is removed from the collar member, the spring-actuating means return to a relaxed equilibrium state thereby closing the outer manhole channel via the channel-gating structure for preventing matter from passing through the outer manhole channel.

Other objects of the present invention, as well as particular features, elements, and advantages thereof, will be elucidated or become apparent from, the following description and the accompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features of my invention will become more evident from a consideration of the following brief descriptions of patent drawings:

FIG. 1 is a longitudinal cross-sectional depiction of a manhole skirt assembly of the present invention showing a multi-piece inner isolation wall and an outer isolation wall and a manhole lid.

FIG. 2 is a longitudinal cross-sectional depiction of the outer isolation wall of the present invention and a manhole lid.

FIG. 3 is a fragmentary longitudinal cross-sectional depiction of a first alternative arrangement of the inner and outer isolation walls depicting non-partitioned inner and outer isolation walls.

FIG. 4 is a fragmentary longitudinal cross-sectional depiction of a second alternative arrangement of the inner and outer isolation walls depicting a non-partitioned inner isolation wall and a transversely partitioned outer isolation wall.

FIG. 5 is a fragmentary longitudinal cross-sectional depiction of a third alternative arrangement of the inner and outer isolation walls depicting a transversely partitioned inner isolation wall and a non-partitioned outer isolation wall.

FIG. 6 is a fragmentary longitudinal cross-sectional depiction of a preferred arrangement of the inner and outer isolation walls depicting a wrapped and perforated outer isolation wall and moisture pathway through the outer manhole channel.

FIG. 7 is a fragmentary longitudinal cross-sectional depiction of the superior end of the manhole skirt assembly positioned adjacent spillage containment structure.

FIG. 8 is a fragmentary longitudinal cross-sectional depiction of a preferred arrangement of the inner and outer isolation walls depicting channel-stabilizing structure extending intermediate the inner and outer isolation walls.

FIG. 9 is a fragmentary longitudinal cross-sectional depiction of the superior end of the manhole skirt assembly depicting a collar assembly in a lid-compressed—open outer manhole channel state.

FIG. 10 is a fragmentary longitudinal cross-sectional depiction of the superior end of the manhole skirt assembly depicting the collar assembly in a lid-removed—closed outer manhole channel state.

FIG. 11 is an end view depiction of first and second knocked-down, stackable, longitudinally-sectioned isolation wall arc lengths.

FIG. 12 is an end view depiction of four knocked-down, stackable, longitudinally-sectioned isolation wall arc lengths.

FIG. 13 is a longitudinal cross-sectional depiction of a manhole skirt assembly of the present invention showing a single-piece inner isolation wall and an outer isolation wall and a manhole lid.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to the drawings, a preferred embodiment of the present invention concerns a manhole assembly 10 generally designed for use in combination with an underground tank assembly and generally illustrated and referenced in FIGS. 1 and 3-10. The manhole assembly 10 of the present invention preferably comprises double walled skirt assembly for supporting a manhole lid 11 as further illustrated and referenced in FIGS. 1, 2, 6, 7, 9, and 10. It is noted that manhole lids 11 are typically constructed from fiberglass or other composites, steel, and/or polyethylene type materials. It may be understood from a consideration of the noted figures as well as from a consideration of the prior manhole lid art that the manhole lid 11 essentially comprises a superior lid surface 12 and an inferior lid surface 13. The skirt assembly of the present invention supports the manhole lid 11 via the inferior manhole lid surface 13.

The manhole assembly 10 or skirt assembly of the present invention is thus preferably double-walled and lid-supporting. The lid-supporting skirt is preferably constructed from fiberglass or other composites, steel, and/or polyethylene type materials and comprises an inner isolation wall 20 as illustrated and referenced in FIGS. 1, 3-10; an outer isolation wall 21 as illustrated and referenced in FIGS. 1-10, a superior skirt end 22 as generally referenced in FIGS. 1, 2, and 5-10; and an inferior skirt end 23 as generally referenced in FIGS. 1, 2, 5, 6, and 8. It may be seen that the inner isolation wall 20 defines an inner manhole 20 cavity as at 24 in FIGS. 1, and 5-10; and a moisture-directing, outer manhole channel as at 25 in FIGS. 1, 3-10. The outer manhole channel 25 thus extends intermediate the inner isolation wall 20 and the outer isolation wall 21. The inner isolation wall 20 may well function to support or contribute to the support of the manhole lid 11 at the inferior lid surface 13 as generally depicted in FIGS. 1, 6, and 7. The outer manhole channel 25 functions to direct moisture 100 as at vector arrows 101 from the superior lid surface 12 to the inferior skirt end 23 in FIG. 6. FIG. 7 further depicts moisture 100 entering the outer manhole channel 25 at the superior skirt end 22. It is thus contemplated that the outer manhole channel 25 effectively functions to otherwise isolate the inner manhole cavity 24 from channel-directed moisture 100.

In the preferred embodiment, it may be seen that the outer isolation wall 21 of the manhole or skirt assembly 10 is preferably bell-shaped as perhaps most clearly depicted in FIGS. 1 and 2. In other words, the outer isolation wall 21 comprises a pronounced inferior wall portion as compared to the superior wall portion. From an inspection of the noted figures, as well as from a consideration of FIGS. 3-6 and 8, it may be understood that the bell-shaped outer isolation wall 21 maximizes the radial distance intermediate the inner and outer isolation walls 20 and 21 at the inferior skirt end 23. It is contemplated that the maximized radial distance may well function for enhancing moisture redirection away from the inner manhole cavity 24 insofar as the maximized radial distance or relatively larger lower open end of the outer manhole channel 25 enables enhanced hydraulic flow through the outer manhole channel 25.

Although it is contemplated that inner isolation wall 20 may be formed as a single piece unit as generally depicted in FIG. 13, it is further contemplated that as means to ease stowage space, transport, and/or installation of the manhole or skirt assembly 10 of the present invention, inner isolation wall 20 and/or the outer isolation wall 21 may be formed in knock-down pieces, attachable to one another for integrally effecting a unit wall, as the case may be. In other words, given skirt assembly having a generally circular transverse cross-section, the wall-forming pieces may comprise two or more portions having certain arc lengths, which, when assembled, form a unitary circle. In this regard, the reader is directed in FIG. 1 which shows a left inner wall portion 30 and a right inner wall portion 31, and FIG. 2 which shows a left outer wall portion 40 and a right outer wall portion 41. When bolted or otherwise attached to one another as at 32, the left and right inner wall portions 30 and 31 form a semi-circular (i.e. 180°) inner wall portion 34 (FIG. 1 depicting a longitudinal cross-section through the diameter of manhole assembly 10). Two semi-circular inner wall portions 34 may be bolted or otherwise attached to one another to form a unitary inner isolation wall 20. The individual inner wall portions, whether semi-circular portions 34, quarter-circle portions 35 (or similar other arc length portions), may be stacked or nested as generally and comparatively depicted in FIG. 11 versus FIG. 12. The individual outer wall portions may be similarly stacked or nested when in a disassembled state and bolted or otherwise attached to one another as at 42 in FIG. 2 when in an assembled state.

Similarly, it is contemplated that superior wall portions may be attachable to inferior wall portions for ease of stowage space, transport, and/or installation. In other words, the inner and outer isolation walls 20 and 21 may be transversely segmented and thus may comprise at least one upper annular portion and at least one lower annular portion, radially nestable inside one another. In this regard, the reader is directed to FIGS. 4 and 5. From an inspection of FIG. 4, it will be seen that outer isolation wall 21 may preferably comprise an upper outer wall portion 36 and a lower outer wall portion 37, which may be bolted or otherwise attached to one another as at 43. Similarly, from an inspection of FIG. 5, it will be seen that inner isolation wall 20 may preferably comprise an upper inner wall portion 38 and a lower inner wall portion 39, which may be bolted or otherwise attached to one another as at 44.

It is further contemplated that the outer isolation wall 21 of the manhole or skirt assembly 10 of the present invention may comprise perforations 50 as generally depicted and referenced in FIG. 6. Moisture 100 may thus enter the outer manhole channel 25 as at 51 for enhancing moisture drainage. Further, it is contemplated that the outer isolation wall 21 may be wrapped with a moisture-permeable wrap 52 as generally depicted and referenced in FIG. 6. It is contemplated that the moisture-permeable wrap 52 of the present invention may be wrapped about the outer isolation wall 21 for preventing debris and/or backfill material 75 from entering the perforated outer isolation wall 21.

In this last regard, it should be readily understood that the typical underground tank assemblies and/or manhole assemblies are usually buried, in part, by backfill material 75 such as gravel and/or sand. For purposes of the present invention, it is recommended that ⅛-inch, self-compacting pea gravel be used as backfill material 75, which backfill material (region) 75 is generally referenced in FIGS. 6 and 7. The backfill material 75 is most usually covered by a surface layer 73 such as a concrete slab or asphalt paving as further generally illustrated and referenced in the noted figures. Typically a concrete pad or slab is poured on top of the underground storage tank system and around the manholes cooperatively associated therewith. It is contemplated that surface layer 43 is preferably graded to otherwise direct matter away from any intermediate structure (such as a manhole lid and/or skirt assembly). The finished primary grade 41 of concrete slab, for example, may preferably have a gradual 3-inch pitch from the top of the manhole area to the substantially horizontal flat grade of the surrounding concrete slab. Outer isolation wall 21 is a part of drain trough, moisture-directing channel, or gutter system and also functions as an isolation wall for preventing the backfill material 75 from entering areas inwardly adjacent to the skirt assembly 10.

The manhole or skirt assembly 10 may further preferably comprise a collar assembly 60 as generally illustrated and referenced in FIGS. 9 and 10. It may be seen from an inspection of the noted figures that collar assembly 60 essentially functions to interface intermediate the lid 11 and the inner isolation wall 20 and thus is cooperably associated with the superior end of the inner isolation wall. The collar assembly 60 preferably comprises a collar member 61 and spring-actuating means (as at 62 in FIG. 10). The collar assembly 60 may be alternatively cooperably associated with a manhole lid ring 67 or collar-engaging structure as generally illustrated and referenced in FIGS. 9 and 10. The spring-actuating means essentially function to spring-actuate the collar member 61. The collar member 61 further preferably comprises certain channel-gating structure 63 as illustrated and referenced in FIGS. 9 and 10. The lid 11 inherently has considerable weight as at vector arrow 63 in FIGS. 9 and 10, which weight is sufficient to elastically compress the spring-actuating means 62 as comparatively depicted.

In other words, the spring-actuating means 62 are compressed when the lid 11 is seated upon the collar member 61 thereby opening the outer manhole channel 25 via the channel-gating structure 63 for allowing matter such as moisture 100 to pass through the outer manhole channel 25 as generally depicted in FIG. 9. Comparatively, FIG. 10 depicts the spring-actuating means 62 in a relaxed equilibrium state when the lid 11 is removed from seated engagement upon the collar member 61 thereby closing the outer manhole channel 25 via the channel-gating structure 63 for preventing matter (such as moisture 100 and/or debris) from passing through the outer manhole channel 25. A closure ring 68 may be cooperatively associated with the channel-gating structure 63 for enhancing the effectiveness of the channel-closing feature exhibited during lid 11 removal. In this regard, it may be understood from a consideration of FIG. 10 that closure ring 68 and channel-gating structure 63 as sized and shaped to mate when the lid 11 is removed and the spring-actuating means 62 return to the relaxed equilibrium state as generally depicted in FIG. 10.

It is thus contemplated that the manhole assembly 10 of the present invention may preferably comprise certain channel debris-filtering means preferably definable by the foregoing or as alternatively defined by certain mesh-like filtering structure 64 as generally illustrated and referenced in FIG. 7. In this regard, it should be noted that it is preferable to keep the outer manhole channel 25 clear from debris so as to maintain the moisture-directing passageway achieved thereby. In other words, it is contemplated that the channel debris-filtering means of the present invention essentially function to filter channel-located debris and prevent clogging of the outer manhole channel 25.

Further, it is contemplated that the outer manhole channel 25 should be of uniform size intermediate the transverse perimeter(s) of the inner and outer isolation walls 20 and 21. In this regard, it is further contemplated that the manhole assembly 10 may preferably comprise certain channel-stabilizing means extendable intermediate the inner and outer isolation walls 20 and 21 for maintaining a substantially uniform distance therebetween. The reader is directed to FIGS. 7 and 8, which figures depict certain means for maintaining the distance intermediate the inner and outer isolation walls or certain channel-stabilizing means. These means may be preferably defined by fasteners as at 65 in FIG. 7 and/or certain mechanical stop structure 66 as generally depicted in FIG. 8.

Inner isolation wall 20 supports the manhole lid 11 in superior adjacency to structure (such as spillage containment structure 70 referenced in FIG. 7) located in cavity 24. The manhole assembly 10 of the present invention may further preferably comprise a lid-support structure 80 intermediate outer isolation wall 21 and inferior lid surface 13 at superior skirt end 22 as referenced in FIGS. 1, 2, and 6-10. Lid-support structure 80 is preferably sized and shaped to seatedly the manhole lid 11. The lid-support structure 80 further preferably comprises a lid-support portion 81 and a lid-centering portion 82 or lid-centering means as further illustrated and referenced in the noted figures.

Notably, inner isolation wall 20 is cooperatively associated with lid-support portion 81 for enhancing support of the lid 11 and for directing diverted moisture 100 through outer manhole channel 25. In this regard, it is contemplated that inner isolation wall 20 may comprise a diverted portion adjacent superior skirt end 22. It will be seen from an inspection of FIGS. 6 and 7, for example, that the diverted superior portion(s) of inner isolation wall 20 function to maintain a substantially uniform channel width at outer manhole channel 25 adjacent lid-support portion 81. Both lid-support portion 81 and inner isolation wall 20 thus function to support the lid 11 at inferior manhole surface 13, and the path for moisture 100 is preferably diverted adjacent the inferior lid surface 13 to provide certain filtering-enablement means.

Inner isolation wall 20 may preferably be truncated or made longitudinally shorter than outer isolation wall 21 as generally depicted in FIGS. 8 and 13. It is contemplated that the reason(s) for having the inner isolation wall 20 slightly shorter than the outer isolation wall 21 would be, as follows: (1) a shorter inner isolation wall 20 allows space between the bottom/backfill material 75 and the bottom of the inner isolation wall 20 for movement should the surface layer 73 or concrete slab holding the manhole lid 11 move up or down; (2) the inner isolation wall 20 can be removed and replaced and the space created by a shorter inner isolation wall 20 will allow a new/replacement inner isolation wall 20 to be easily installed; (3) a shorter inner isolation wall 20 provides a larger drainage space at the bottom, and also eliminate the potential of a dam forming between the inner and outer isolation walls 20 and 21. It is thus contemplated that the inner isolation wall may be preferably truncated relative to the outer isolation wall, the truncated inner isolation wall for enhancing the effectiveness of the manhole assembly.

It may be further understood that the components of the present invention may well function to provide a manhole conversion kit or manhole kit for outfitting an underground tank assembly, which kit may preferably be said to essentially comprise a knock-down type skirt assembly such as manhole assembly 10. In this regard, it may be said that the knock-down skirt assembly preferably comprises a plurality of transverse or longitudinal inner wall portions and a plurality of transverse or longitudinal outer wall portions. The inner wall portions are preferably attachable to one another to form an inner isolation wall such as wall 20; and the outer wall portions are preferably attachable to one another to form an outer isolation wall such as wall 21. The inner and outer isolation walls are thus cooperable to form a double-walled skirt assembly, whereby the inner isolation wall defines an inner manhole cavity and a moisture-directing, outer manhole channel. The outer manhole channel extends intermediate the inner isolation wall and the outer isolation wall, and the inner isolation wall may well function to support a manhole lid 11 at the inferior lid surface.

While the foregoing specifications contain much specificity, this specificity should not be construed as limitations on the scope of the invention, but rather as an exemplification of the invention. For example, as is implicit in the foregoing descriptions the present disclosure may further be said to disclose a moisture-redirection assembly for use in combination with a manhole. The moisture-redirection assembly essentially comprises a double-walled skirt assembly comprising inner and outer isolation walls. The inner isolation wall defines an inner manhole cavity and an outer manhole channel. The outer manhole channel extends intermediate the inner and outer isolation walls. The inner isolation wall functions to supporting a manhole lid and the outer manhole channel functions to direct moisture away from the inner manhole cavity. The skirt assembly may further comprise certain channel-gating means preferably defined by a spring-actuable collar assembly interfacing intermediate a manhole lid and the inner isolation wall. The collar assembly may be lid-compressible for selectively allowing matter to pass through the outer manhole channel. The channel-gating means are thus cooperable with the manhole lid for selectively allowing matter to pass through the outer manhole channel.

The outer isolation wall may comprise a plurality of outer wall portions attachable to one another for forming the outer isolation wall, and for decreasing stowage space of the outer isolation wall when in a knock-down state. Similarly, the inner isolation wall may comprise a plurality of inner wall portions attachable to one another to form the inner isolation wall, and for decreasing stowage space of the inner isolation wall when in a knock-down state. The outer isolation wall may be bell-shaped for maximizing the radial distance intermediate the inner and outer isolation walls at an inferior end thereof. The noted maximized radial distance may well function to enhance moisture redirection away from the inner manhole cavity. Further, the outer isolation wall may be perforated for enhancing moisture drainage, and may comprise a moisture-permeable wrap for preventing debris from entering the perforated outer isolation wall.

Thus, although the invention has been described by reference to a preferred embodiment, it is not intended that the novel assembly or kit be limited thereby, but that modifications thereof are intended to be included as falling within the broad scope and spirit of the foregoing disclosure, the following claims and the appended drawings. 

1. A manhole assembly for use in combination with an underground tank assembly, the manhole assembly comprising: a lid and a skirt assembly, the lid comprising a superior lid surface and an inferior lid surface, the skirt assembly comprising a double-walled, lid-supporting skirt, the lid-supporting skirt comprising an inner isolation wall, an outer isolation wall, a superior skirt end, and an inferior skirt end, the inner isolation wall defining an inner manhole cavity and a moisture-directing, outer manhole channel, the outer manhole channel extending intermediate the inner isolation wall and the outer isolation wall, the inner isolation wall supporting the manhole lid at the inferior lid surface, the outer manhole channel directing moisture from the superior lid surface to the inferior skirt end thus isolating the inner manhole cavity from channel-directed moisture.
 2. The manhole assembly of claim 1 wherein the outer isolation wall is bell-shaped, the bell-shaped outer isolation wall for maximizing the radial distance intermediate the inner and outer isolation walls at the inferior skirt end, the maximized radial distance for enhancing moisture redirection away from the inner manhole cavity.
 3. The manhole assembly of claim 2 wherein the outer isolation wall comprises an upper annular portion and a lower annular portion, the upper and lower annular portions being attachable to one another for effecting the bell-shaped outer isolation wall.
 4. The manhole assembly of claim 1 wherein the inner isolation wall comprises a plurality of arc length portions, the arc length portions being attachable to one another to form a cylindrical inner isolation wall, the plurality of arc length portions for decreasing stowage space of the inner isolation wall when in a knock-down state.
 5. The manhole assembly of claim 1 wherein the outer isolation wall is perforated, the perforated outer isolation wall for enhancing moisture drainage.
 6. The manhole assembly of claim 5 comprising a moisture-permeable wrap, the moisture-permeable wrap being wrapped about the outer isolation wall for preventing debris from entering the perforated outer isolation wall.
 7. The manhole assembly of claim 1 comprising channel-stabilizing means, the channel-stabilizing means for extending intermediate the inner and outer isolation walls for maintaining a substantially uniform distance therebetween.
 8. The manhole assembly of claim 1 comprising channel debris-filtering means, the channel debris-filtering means for filtering channel-located debris and for preventing clogging of the outer manhole channel.
 9. The manhole assembly of claim 1 comprising a collar assembly, the collar assembly interfacing intermediate the lid and the inner isolation wall, the collar assembly comprising a collar member and spring-actuating means, the spring-actuating means for spring-actuating the collar member, the collar member comprising channel-gating structure, the spring-actuating means being compressed when the lid is seated upon the collar member thereby opening the outer manhole channel via the channel-gating structure for allowing matter to pass through the outer manhole channel, the spring-actuating means being relaxed when the lid is removed from the collar member thereby closing the outer manhole channel via the channel-gating structure for preventing matter from passing through the outer manhole channel.
 10. The manhole assembly of claim 1 wherein the inner isolation wall is truncated relative to the outer isolation wall, the truncated inner isolation wall for enhancing the effectiveness of the manhole assembly.
 11. A manhole kit, the manhole kit for outfitting an underground tank assembly, the manhole kit comprising: a knock-down skirt assembly, the knock-down skirt assembly comprising a plurality of inner wall portions and a plurality of outer wall portions, the inner wall portions being attachable to one another to form an inner isolation wall, the outer wall portions being attachable to one another to form an outer isolation wall, the inner and outer isolation walls being cooperable to form a double-walled skirt assembly, the inner isolation wall defining an inner manhole cavity and a moisture-directing, outer manhole channel, the outer manhole channel extending intermediate the inner isolation wall and the outer isolation wall, the inner isolation wall supporting the manhole lid at the inferior lid surface, the outer manhole channel directing moisture away from the inner manhole cavity.
 12. The manhole kit of claim 11 wherein the outer isolation wall is bell-shaped, the bell-shaped outer isolation wall for maximizing the radial distance intermediate the inner and outer isolation walls at an inferior end thereof, the maximized radial distance for enhancing moisture redirection away from the inner manhole cavity.
 13. The manhole kit of claim 11 wherein the outer isolation wall is perforated, the perforated outer isolation wall for enhancing moisture drainage.
 14. The manhole kit of claim 13 comprising a moisture-permeable wrap, the moisture-permeable wrap being wrapped about the outer isolation wall for preventing debris from entering the perforated outer isolation wall.
 15. The manhole kit of claim 11 comprising channel-stabilizing means, the channel-stabilizing means for extending intermediate the inner and outer isolation walls for maintaining a substantially uniform distance therebetween.
 16. The manhole kit of claim 11 comprising a lid-support structure, the lid support structure being extendable intermediate the outer isolation wall and a manhole lid, the lid-support structure being sized and shaped to seatedly receive the manhole lid, the lid-support structure comprising a lid-support portion and a lid-centering portion, the outer isolation wall being cooperatively associated with the lid-support portion for enhancing support of the manhole lid and for directing diverted moisture through the outer manhole channel.
 17. The manhole kit of claim 11 comprising a spring-actuable collar assembly, the collar assembly interfacing intermediate a manhole lid and the inner isolation wall and being lid-compressible for selectively allowing matter to pass through the outer manhole channel.
 18. A moisture-redirection assembly for use in combination with a manhole, the moisture-redirection assembly comprising a double-walled skirt assembly, the skirt assembly comprising inner and outer isolation walls, the inner isolation wall defining an inner manhole cavity and an outer manhole channel, the outer manhole channel extending intermediate the inner isolation wall and the outer isolation wall, the inner isolation wall for supporting a manhole lid, the outer manhole channel for directing moisture away from the inner manhole cavity.
 19. The moisture-redirection assembly of claim 17 wherein the outer isolation wall comprises a plurality of outer wall portions, the outer wall portions being attachable to one another for forming the outer isolation wall, the plurality of outer wall portions for decreasing stowage space of the outer isolation wall when in a knock-down state.
 20. The moisture-redirection assembly of claim 18 wherein the inner isolation wall comprises a plurality of inner wall portions, the inner wall portions being attachable to one another to form the inner isolation wall, the plurality of inner wall portions for decreasing stowage space of the inner isolation wall when in a knock-down state.
 21. The moisture-redirection assembly of claim 18 wherein the outer isolation wall is bell-shaped, the bell-shaped outer isolation wall for maximizing the radial distance intermediate the inner and outer isolation walls at an inferior end thereof, the maximized radial distance for enhancing moisture redirection away from the inner manhole cavity.
 22. The moisture-redirection assembly of claim 18 wherein the outer isolation wall is perforated, the perforated outer isolation wall for enhancing moisture drainage.
 23. The moisture-redirection assembly of claim 22 wherein the outer isolation wall comprises a moisture-permeable wrap, the moisture-permeable wrap being wrapped about the outer isolation wall for preventing debris from entering the perforated outer isolation wall.
 24. The moisture-redirection assembly of claim 18 comprising channel-stabilizing means, the channel-stabilizing means extending intermediate the inner and outer isolation walls for maintaining a substantially uniform distance therebetween.
 25. The moisture-redirection assembly of claim 18 comprising channel debris-filtering means, the channel debris-filtering means for filtering channel-located debris.
 26. The moisture-redirection assembly of claim 18 comprising channel-gating means, the channel-gating means being cooperable with the lid for selectively allowing matter to pass through the outer manhole channel. 